FRESNO, California – A worker at a meat processing plant opened fire on co-workers on Tuesday, killing a man and injuring three people before critically wounding himself, police said.

The gunman, identified as Lawrence Jones, 42, opened fire at Apple Valley Farms in Fresno and killed a 32-year-old man, Police Chief Jerry Dyer told reporters.

Jones, who officers found on the sidewalk outside the plant with a self-inflicted gunshot wound to the head, and the four people he shot were all employees of the business, Dyer said.

The gunman reported for work in the morning at the meat processing plant and was there for more than three hours before opening fire with a handgun, Dyer said.

“It’s difficult to say if there was a specific target that Jones was looking for,” Dyer said.

A 34-year-old worker at the plant was shot in the head and a 28-year-old male employee was hit in the neck, Dyer said. Both men were hospitalized in critical condition, police said.

A 32-year-old woman was shot in the lower back, but is in good condition, police said.

Jones has a criminal history dating to the 1990s and was on parole, Dyer said.

(Reporting by Stephen Keleher; Writing by Alex Dobuzinskis; Editing by Stacey Joyce and Bill Trott)